Pinnate leaf arrangement is characterized by a central rachis bearing leaflets on both sides. Which term describes this pattern?

Pinnate leaf arrangement is characterized by a central rachis bearing leaflets on both sides. Which term describes this pattern?

• A. Simple
• B. Palmate
• C. Pinnate
• D. Bipinnate

Answer: (C)

Pinnate arrangement describes a leaf that is a compound leaf with a central axis (the rachis) bearing leaflets along its length on both sides. This creates a feather-like line of leaflets along a single spine, which is why the pattern is called pinnate. It’s different from simple leaves, which are undivided blades; from palmate leaves, where leaflets radiate from a single point at the end of the petiole; and from bipinnate leaves, where the leaflets themselves are subdivided along secondary axes. In a pinnate leaf, you’d see leaflets lined up along the rachis just like feathers along a shaft, which matches the description here.

Pinnate arrangement describes a leaf that is a compound leaf with a central axis (the rachis) bearing leaflets along its length on both sides. This creates a feather-like line of leaflets along a single spine, which is why the pattern is called pinnate. It’s different from simple leaves, which are undivided blades; from palmate leaves, where leaflets radiate from a single point at the end of the petiole; and from bipinnate leaves, where the leaflets themselves are subdivided along secondary axes. In a pinnate leaf, you’d see leaflets lined up along the rachis just like feathers along a shaft, which matches the description here.